Circuit interrupter



W. M. LEEDS ETAL CIRCUIT INTERRUPTER Filed Dec.

April 25, 1961 United States Patent O CIRCUIT INTERRUPTER Winthrop M. Leeds and Alva A. Johnson, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 10, 1957, Ser. No. 701,756

Claims. (Cl. 20G-148) This invention relates to circuit interrupters in general and, more particularly, to circuit intermpters of the compressed-gas type.

A general object of the invention is to provide an improved compressed-gas circuit interrupter, which will be more elective than circuit interrupters of the prior art, and will render improved operation over a wide range of current and voltage ratings.

A more specific object of the invention is to provide an improved compressed-gas circuit interrupter utilizing a sealed are-extinguishing unit containing a sealed gas at relatively high pressure, which gas possesses the properties of being a good arc-quenching gas.

Another object is to provide an improved compressedgas circuit interrupter of the type specified in the irnmediately preceding paragraph, in which the sealed arcextinguishing unit is positioned within a surrounding, substantially closed enclosure containing a gas at a lower pressure. As will be obvious to those skilled in the art, by such a construction the gas at high pressure within the sealed arcextinguishing unit will be most effective for arc extinction, whereas the gas at a relatively low pressure within the surrounding enclosure may be designed particularly for voltage-withstanding ability at the lower pressure, to reduce the cost required for filling the enclosure and to eliminate the necessity for stronger tank walls of the enclosure.

A further object of the present invention is to provide a sealed arc-extinguishing unit containing gas at a relatively high pressure, which unit is supported at one end of a supporting terminal bushing; and a high-pressure reservoir is disposed at the other end of said terminal bushing, with passage means allowing intercommunication between the high-pressure reservoir and the sealed arc-extinguishing unit at high pressure. This has the particular advantage that a high-pressure gauge may be associated with the high-pressure reservoir, so that when the enclosed tank construction is employed, the pressure gauge, being external to said tank, will be visible to station personnel.

Yet a further object of the invention is to provide an improved compressed-gas circuit interrupter of the grounded-tank type, in which a pair of terminal bushings extend interiorly within a grounded metallic tank, wherein the terminal bushings support within the tank high-pressure, sealed arc-extinguishing units, and the ambient gas pressure within the surrounding tank may be at a lower pressure, being designed purely for the voltage-withstanding ability.

Another object is to provide an improved compressedgas circuit interrupter of the dead-tank type, as specified in the immediately preceding paragraph, wherein checkvalve means are associated with each of the supporting terminal bushings, so that the gas at relatively low pressure within the dead tank may leak into the interior of the terminal bushings to improve their voltage-withstanding ability.

A further object of the present invention is to render ICC compressed-gas interrupting units suitable for application within a dead-tank construction, wherein by the means of sealed units different gases may be employed within the dead tank and in the sealed unit, or the same gas may be used at different pressures.

Further objects and advantages will readily become apparent upon reading the following specitication, taken in conjunction with the drawing, in which:

Figure l is a vertical sectional view, with one unit in side elevation, taken through a compressed-gas circuit interrupter, embodying the principles of the present nvention, with the contact structure being illustrated in the partly open-circuit position;

Fig. 2 is an enlarged, fragmentary, vertical sectional view of the left-hand arc-extinguishing unit of Fig. l, with the actuating linkage being illustrated in the closedcircuit position; and,

Pig. 3 is a considerably enlarged, fragmentary view, in vertical cross-section, through a portion of the terminal bushing mounting flange, illustrating, to an enlarged scale, the ball check valve for permitting entrance of gas from the tank to the region within the terminal bushlng.

Referring to the drawing, and more particularly to Fig, l thereof, the reference numeral 1 generally designates a compressed-gas type of circuit interrupter, including a surrounding enclosure, or metal tank 2, enclosing a pair of sealed, arc-extinguishing units 4.

The arc-extinguishing units 4 depend from the lower interior ends of a pair of terminal bushings, generally designated by the reference numeral 5, which extend downwardly through the top of the grounded, dead tank 2.

With particular attention being directed to Figs. 1 and 2, it will be noted that each arc-extinguishing unit 4 includes an upper closure cap 6, having an integrally formed, downwardly projecting, stationary contact 7. The stationary contact 7 cooperates with a movable contact 8, the latter being extended downwardly to form a piston rod 9, to effect vertical, reciprocal movement of a pumping piston 10.

The pumping piston 10 contains a plurality of diagonally extending passages 11, which permit communication between the region 12 below the piston 10 and the region 13 above the piston 10. A movable insulating orifice 14, disposed within a surrounding sleeve 15, is carried by the piston 10, within an upstanding, insulating, operating cylinder 16.

The insulating, upstanding, operating cylinder 16 has its lower end closed by an apertured, metallic, partition plate 17, the latter being affixed to the side insulating wall 18 of the arc-extinguishing unit 4.

Preferably a plurality of openings 19, provided in the partition plate 17, permit gas communication between the upper and lower sides of the partition plate 17.

To effect vertical reciprocating movement of the movable contact 8 into engagement with the stationary contact 7, and to effect separation therebetween, and consequent arc establishment, there is provided an operating linkage, generally designated by the reference numeral 21. This operating linkage 21 may be of any desired type, but it is preferable to provide for straightline movement of the movable contact 8 and the pumping piston 1i). This is brought about by the provision of a floating link 22, pivotally connected at 23 to the lower end of the piston rod 9. The other end of the Heating link 22 is pivotally connected, as at 24, to the lower end of a guide link 25, the upper end of which is pivotally connected at 26 to a laterally jutting, bifurcated bracket 27 ixedly secured to the lower closure cap 28 of the areextinguishing unitA.

As observed in Fig. l, a crank-arm 29 is keyed to a Patented Apr. 25, 1961 horizontally extending, drive shaft 30, the latter extending laterally out of a lower projecting portion 31 of'thc lower closure cap or mechanism housing 28. Since it is desiredto use the same gas within the tank 2 and within unit 4 at dlerent pressures, or, different gases in someY applications, the drive shaft 30 is sealed in a gastight manner as it passes out of the lower portion 31 of mechanism housing 28. Any suitable seal may be employed for the opposite ends of the drive shaft 30 for the ends thereof, which extend through lateral openings in the lower projecting portion 31 of lower housing cap 28. It is preferred, however, to use a exible, gas-tight, shaft seal of the type set out in U.S. Patent application filed April 9, 1956, Serial No. 576,875. now United States Patent,2,889,434, issued June 2, 1959 to Harry I. Lingal, assigned to the assignee of the instant application, to which reference may be made for the details of such a exible, scaling shaft arrangement. For the purpose of understanding the present invention, however, it is only necessary to know that the drive shaft 30 is sealed in a gas-tight manner, as it passes out of lower closure cap 28V to the region 32 within tank 2.

Fixedly keyed to the opposite ends of the drive shaft 30 is a bifurcated crank arm 34, the furcations 35 of which are secured to the outer ends of drive shaft 30. The crank arm 34, in addition, has a bifurcated configuration at its lower extremity to accommodate a drive roller 36. The drive rollers 36 for the two serially related, arc-extinguishing units 4 are engaged by the opposite ends of a conducting crossbar, or bridging member 37, the latter being reciprocally operated in a vertical direction during the opening and closing movements of the interrupter 1.

As illustrated in Fig. l, the actuating member or conducting crossbar 37 is actuated by a lift rod 38, formed of insulating material, and having its upper end connected to any suitable operating mechanism. Since this operating mechanism may be of any suitable type, it is not described herein.

Each terminal bushing includes a hollow terminal stud 40, which defines a passage means 41 permitting intercommunication between a high-pressure gas reservoir 42, disposed externally of the tank 2 at the upper end of the terminal bushing 5 at high potential, and the region 43 within the upper end of the arc-extinguishing unit 4.

Disposed about the tubular terminal stud 40 is a terminal-bushing core 44, which may be provided by a Wrapping of a suitable paper-like material having, if desired, condenser foils interspread therewithin, to consti tute the condenser layers for the terminal bushing 5.

A pair of weatherproof shells 45, 46 may be disposed about the core 44 in compression, as afforded by any suitable compression-spring arrangement, disposed within the upper cap structure 42, as well known by those skilled in the terminal-bushing art. interposed between the porcelain shells 45, 46 is an intermediate grounded supporting ange support 47 having laterally extending ange portions 48, 49, which, through gaskets not shown, engage the opposing inner ends of the porcelain shells 45, 46.

As noted in Fig. l, the upper closure cap 6 for the unit 4 may be threadedly secured to the lower end of the tubular terminal stud 40, and, as illustrated, may bear through gaskets, not shown, against the lower end of the lower porcelain shell 46. Current transformers l50 may be employed, surrounding the ground-flange support 47, for the purpose of measuring current passing through the interrupter and controlling the relaying operations.

Situated in the wall of the iiange sleeve 51 of the ground-flange support 47 is a check valve, generally designated by the reference numeral 52, and more clearly shown in Fig. 3 of the drawing.

With reference to Fig. 3, it will be observed that the valve means 52 includes a ball valve 53, biased by a cornpression spring 54 over an opening 55 in fiange sleeve 51. A U-shaped bracket 56 supports the comprsion spring 54, and controls the movement of the ball valve 53. Thus, when the pressure within the region 57 (Fig. l) within the terminal bushing 5 drops a considerable amount, the pressure of the gas in the region 32 within tank 2, may overcome the biasing action exerted by the compression spring 54, and permit unseating of the ball valve 53 away from the opening 55, to permit thereby gas to flow from the region 32, within tank 2, through opening `55 and into the region 57 within terminal bushing 5, to increase the voltage-withstanding ability of the terminal bushing 5;

In the closed-circuit position of the interrupter 1, the circuit therethrough extends from the terminal 58 through reservoir cap 42, through tubular terminal stud 40, upper closure cap 6, stationary contact 7, movable contact 8, piston rod 9, through the conducting linkage 21 and through roller 36 to the left-hand end of the conducting crossbar 37. The circuit then extends through the righthand, arc-extinguishing unit 4 in an identical manner.

To effect the opening of the circuit interrupter, suitable external mechanism, not shown, is actuated to eiect downward, opening movement of the operating, or lift rod 38. This effects downward, opening movement of the crossbar 37, permitting the accelerating compression springs 59, within the casings 18 to move the piston rods 9 downwardly so that the rollers 36 maintain contact with the crossbar 37.

It will be obvious that downward, opening movement of the movable contact 8 will establish an arc 60 between the stationary and movable contacts 7, 8; and, simultaneously, the downward movement of the oriice `14 with the pumping piston `10 will result in gas being placed under pressure Within the region 12. This gas will flow upwardly through the diagonally extending passages 1l, through the orifice 61, as defined by the orifice member 14, into engagement with the arc 60 to eiect the extinction thereof. A similar action occurs within the righthand, arc-extinguishing unit 4. The circuit is consequently interrupted, and continued, downward, opening movement of the left rod 38 and crossbar 37 will introduce the two isolating gaps at the rollers 36.

To effect the reclosure of the circuit controlled by the interrupter 1, the external mechanism is actuated to effect the raising of the lift rod 38. This raises crossbar 37 until it engages the rollers 36, to actuate the operating crank means, at which time the linkage 2l is moved to the position shown in Fig. 2, with resulting contact closure.

`It will be observed that with the construction illustrated, and described as aforesaid, that, for example, a gas, such as SP6 or SeF, as mixtures of one or both of the aforesaid gases with air, nitrogen, argon, helium, or carbon dioxide may be employed within the sealed unit 4. This gas is maintaned at high gas pressure since, as known to those skilled in the art, arc-rupturing effectiveness of a gas is increased by increasing the pressure thereof.

As a result, the sulfur hexauoride, or the selenium hexauoride, or the aforesaid mixture, as illustrative examples, may be at a pressure of say 50 to l0() pounds per square inch within the r-egion 43 of the unit 4. A similar gas may be provided within the region 32 within the tank 2 at a lower pressure, say l5 to 30 pounds per square inch, or a different gas not necessarily suitable for arc quenching say, for example, perchloryluoride (ClO3F) may be employed as the dielectric gas within the main tank 2. When it is desired to utilize a terminal bushing, which is not oil filled, the gas disposed within the region 32 of tank 2 at the relatively low pressure may be permitted to be employed in connection with the terminal bushings 5, entering into the region 57 within the porcelain casings 45, 46 thereof, as controlled by the valve means 52.

From the foregoing it will be apparent that there is provided a dual-pressure, dead-tank construction for a compressed-gas circuit interrupter. The invention may be applied to a steel-tank circuit interrupter filled with a high-dielectric strength gas, such as SFB at relatively low pressure, say from to 30 p.s.i., while interrupting chambers 4, sealed off from the rest of the tank 2, utilize gas at a higher pressure, say 50 to 100 p.s.i. to obtain the required arc-rupturing effectiveness.

If the steel tank 2 were filled to the higher pressure, undue cost for the extra gas and stronger tank walls would be involved. Instead of using oil-filled bushings, an opening in the bushing to the tank 2 provides impregnating gas, not contaminated by arcing, and at a low pressure so as not to overstress the bushing porcelain weather casings 45, 46.

To add high-pressure gas volume and to provide a pressure gauge 62 visible externally, the hollow terminal stud 40 communicates between the high-pressure interrupter chamber 4 and a high-pressure reservoir 42 in the terminal bushing cap.

interrupting action is obtained by pumping high-pressure gas through the orifice 61 around the contacts 7, S, using energy from the accelerating springs 59. These accelerating springs 59 are compressed, and the contacts 7, 8 are closed, by the operating linkage 21 operated through a sealed shaft 30 from a crank and roller 36 lifted by the main breaker cross-arm 37.

It is an important feature of the invention that the low pressure within the tank 2 may be a ditferent gas from the high-pressure gas provided within the sealed arc-extinguishing units 4. This has the distinct advantage that one gas may be selected for the main tank 2 with the best dielectric properties, whereas the other gas for the units 4 may be selected for the best arc-quenching action.

`It will be apparent that should leakage occur about the upper terminal-bushing weatherproof shell 4S, that the loss of pressure will permit the valve means 52 to function so that gas may be replaced within the terminal bushing S, being taken from the main breaker tank 2. On the other hand, should a leak occur within the main tank 2 so that the pressure therein drops to zero, still the provision of the check valve 52 associated with each terminal bushing 5 will permit the gas within the region 57 of each terminal bushing to be trapped therein, resulting in the terminal bushing maintaining its high-voltage withstanding ability, even though the pressure has been lost in the main tank 2.

From the foregoing description it will be apparent that there is provided a novel compressed-gas circuit interrupter, adapted for the use of the same gas at different pressures, or different gases at diiferent pressures. The gas within the tank 2 is selected for its dielectric properties, whereas the gas within the units 4 may be selected for the arc-interrupting characteristics thereof and may be maintained at a high pressure for increased arc effectiveness. Since the volume within the units 4 is relatively small, there is a saving in expense since the arcquenching gas at high pressure does not lill the large surrounding enclosure 2.

The invention moreover permits the use of the same gas within the tank 2, selected for its dielectric characteristics, to be employed within the terminal bushings 5, when an oil-filled bushing is not desired. The reservoir 42 at the outer end of the terminal bushing may be used, of course, even though an oil-filled bushing were employed The high-pressure reservoir 42 maintains the pressure within the units 4 and also provides a ready means for pumping up the gas at high pressure within the units 4.

Although there has been shown and described a speciiic structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

We claim as our invention:

l. The combination in a tank-type compressed-gas circuit interrupter of a grounded metallic tank, a pair of terminal bushings extending into the tank, a pair of sealed rigid-wall pressurized gas-filled arc-extinguishing units containing a gas comprising sulfur hexauoride under pressure, the gas pressure within the sealed pressurized arc-extinguishing units being at least 50 pounds per square inch for highly effective interrupting performance, means supporting said pressurized rigid-wall arcextinguishing units interiorly within the grounded tank vadjacent the interior ends of the two terminal bushings, means sealing the interior of said gas-filled units from the ambient within the surrounding tank, contact means separable within each sealed pressurized arc-extinguishing unit to establish an arc therein, operating crank means including a sealed rotatable drive shaft extending through the rigid wall of each unit, an operating crank arm secured to each sealed drive shaft and disposed externally of the respective pressurized unit, connecting means interconnecting the interior end of each rotatable drive shaft with the respective separable contact means for effecting the opening and closing movements thereof, and a conducting cross-bar for electrically connecting the pair of arc-extinguishing units in series and also for operating said externally located crank arms.

2. The combination in a tank-type compressed-gas high-power circuit interrupter of a grounded metallic tank, a terminal bushing extending interiorly within said tank, means supporting an arc-extinguishing unit adjacent the interior end of the terminal bushing, a gas-tight seal being provided between the arc-extinguishing unit and the ambient within the surrounding tank, an arcextinguishing gas under pressure within said arc-extinguishing unit, means for establishing an arc within said arc-extinguishing unit, means associated with said arcextinguishing unit to effect the extinction of said arc, a high-pressure gas reservoir disposed at the external end of said terminal bushing and at high potential, and passage means interconnecting said high-pressure gas reservoir through said terminal bushing with the sealed arcextinguishing unit.

3. The combination in a tank-type compressed-gas circuit interrupter of a grounded metallic tank, a pair of terminal bushings extending into the tank, a pair of sealed rigid-wall pressurized gas-filled arc-extinguishing units containing a gas comprising sulfur hexailuoride under pressure, the gas pressure within the sealed pressurized arc-extinguishing units being at least 50 pounds per square inch for highly effective interrupting performance, means supporting said pressurized rigid-wall arcextinguishing units interiorly within the grounded tank adjacent the interior ends of the two terminal bushings, means sealing the interior of said gas-lled units from the ambient within the surrounding tank, contact means separable within each sealed pressurized arc-extinguishing unit to establish an arc therein, operating crank means including a sealed rotatable drive shaft extending through the rigid wall of each unit, an operating crank arm secured to each sealed drive shaft and dispoesd externally of the respective pressurized unit, connecting means interconnecting the interior end of each rotatable drive shaft with the respective separable contact means for effecting the opening and closing movements thereof, piston means disposed interiorly within each unit and operable in accordance with opening movement of the separable contact means for effecting circulation of the high-pressure gas within each unit to increase the interrupting capacity of the unit, and a conducting cross-bar for electrically connecting the pair of arc-extinguishing units in series and also for operating said externally located crank arms.

4. A dead-tank compressed-gas high power circuit interrupter including a grounded metallic dead tank having a pair of terminal bushings extending therein, means supporting a pair of serially related arc-extinguishing units adjacent the interior ends of said terminal bushings, a gas at relatively low pressure within said grounded tank, gas at a higher pressure disposed within said arc-extinguishing units, said arc-extinguishing units being sealed from the ambient within said tank, contact means for establishing an arc within each arc-extinguishing unit, a conducting crossbar for effecting the opening motion of said contact means, high-pressure gas reservoirs disposed at the external ends of said terminal bushings and at high potential, and passage means interconnecting said high-pressure reservoirs through said terminal bushings with the sealed arc-extinguishing units.

5. A tank-type compressed-gas circuit interrupter including a grounded metallic tank, a pair of terminal bushings extending into the tank, a pair of sealed rigid-wall pressurized gas-filled arc-extinguishing units containing a gas comprising sulfur hexauoride under pressure, the gas pressure within the sealed pressurized arc-extinguishing 1units being at least 50 pounds per square inch for highly effective interrupting performance, means supporting said pressurized rigid-wall arc-extinguishing units interiorly within the grounded tank adjacent the interior ends of the two terminal bushings, means sealing the interior of said gas-filled units from the ambient within the surrounding tank, each arc-extinguishing unit including a cylindrical insulating casing and a lower mechanism housing, contact means separable within each sealed pressurized arc-extinguishing unit to establish an arc therein, operating crank means including a sealed rotatable drive shaft extending through the rigid wall of each unit, an operating crank arm secured to each sealed drive shaft and disposed externally of the respective pressurized unit, said sealed drive shaft being journaled Within said mechanism housing, connecting means interconnecting the interior end of each rotatable drive shaft with the respective separable contact means for eir'ecting the opening and closing movements thereof, and a conducting cross-bar for electrically connecting the pair of arc-extinguishing units in series and also for operating said externally located crank arms.

6. A circuit interrupter of the gas-blast type including a sealed arc-extinguishing unit, gas under pressure within said sealed unit, a terminal bushing supporting said unit at one end thereof and containing `a high-pressure gas reservoir at the other end thereof at high potential, passage means within said terminal bushing connecting said high-pressure gas reservoir with said arc-extinguishing unit, piston means disposed within said unit for forcing gas through an established arc therein, and a surrounding enclosure containing gas at a diierent pressure.

7. The combination in a tank-type compressed gas circuit interrupter of a grounded metallic tank, a terminal bushing extending interiorly within said tank and supporting an arc-extinguishing unit at the interior end thereof, means forming a gas-tight seal between the arc-extinguishing unit and the ambient within the surrounding tank, an arc-extinguishing gas under pressure within said arc-extinguishing unit, means for establishing an arc within said arc-extinguishing unit, means associated with said arc-extinguishing unit to etect the extinction of said arc, a high-pressure gas reservoir disposed at the external end of said terminal bushing and at high potential, passage means interconnecting said high-pressure gas reservoir through said terminal bushing with the sealed arcextinguishing unit, and a pressure gauge at the highpressure reservoir end of the terminal bushing for indicating visibly externally of said tank the pressure within said arc-extinguishing unit.

8 8. A dead-tank compressed-gas high-power circuit interrupter including a grounded metallic dead tank having a pair of terminal bushings extending therein, a pair of serially related arc-extinguishing units supported at the interior ends of said terminal bushings, a gas at relatively low pressure within said grounded tank, gas at a higher pressure disposed within said arc-extinguishing units, said arc-extinguishing units being sealed from the ambient within said tank, Contact means for establishing an arc within each arc-extinguishing unit in the ambient of higher gas pressure, a conducting cross bar for eiecting the opening motion of said contact means, and oontinued opening movement of the conducting cross bar providing a pair of serially related isolating gaps in the circuit.

9. A highpower circuit interrupter of the compressedgas type including a grounded metallic tank pressurized with gas at a relatively low gas pressure, a pair of highvoltage terminal bushings extending interiorly within said grounded metallic tank and carrying a pair of sealed arcextinguishing units at their interior ends, a conducting cross bar for electrically interconnecting the two arc-extinguishing units, each arc-extinguishing unit being pressurized with a relatively high pressure gas, at least a pair of separable contacts within each arc-extinguishing unit separable within high-pressure gas, spring means associated with each arc-extinguishing unit responsive to opening motion of the conducting cross bar for eiecting opening separation of each pair of separable contacts, and continued opening movement of the conducting cross bar providing Ia pair of serially related isolating gaps in the circuit.

10. The combination in a tank-type compressed-gas high-power circuit interrupter of a grounded metallic tank, means supporting a pair of serially related sealed pressurized arc-extinguishing units interiorly within said grounded metallic tank, said grounded tank containing gas at a relatively low pressure but higher than atmospheric pressure, the pressure within the pressurized arcextinguishing units being higher than the tank pressure, separable contact means disposed within said arc-extinguishing unit, a conducting cross bar for electrically interconnecting the two arcextinguishing units, means responsive to opening motion of said conducting cross bar for etecting separation of each separable contact means, and continued opening movement of the conducting cwss bar providing a pair of serially related isolating gaps in the circuit.

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